OBJECTIVESTo investigate the neuroprotective function of alpha 3 nicotinic acetylcholine receptor (nAChR) by inhibiting the gene expression in human neuroblastoma (SH-SY5Y) cells using small interference RNA (siRNA).

METHODSThe siRNA coding oligonucleotide sequences targeting alpha 3 nAChR were designed and synthesized. The annealed product was cloned into pSilencer 3.1-H1 neo vector. The recombinant alpha 3 nAChR pSilencer 3.1-H1 neo vector was transfected into the SH-SY5Y cells. The stable clones were screened by G418 medium, and the levels of alpha 3 nAChR mRNA and protein were monitored by using real-time PCR and Western blotting, respectively. After the SH-SY5Y cells with siRNA treatment were exposed to 1 micromol/L Abeta(1-42), MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide], SOD, GSH-px and the lipid peroxidation were measured by spectrophotometry.

RESULTSCompared with the controls, the expression levels of mRNA and protein in the stable SH-SY5Y clone cells transfected with the recombinant alpha 3 nAChR pSilencer 3.1-H1 neo vector were decreased with inhibitory efficiency of 98% and 66%, respectively, the MTT reduction decreased; the product of lipid peroxidation was increased and the activities of SOD and GSH-px were decreased. Biologically, the gene expression inhibition of alpha 3 nAChR enhanced the toxicity induced by Abeta in SH-SY5Y cells.

CONCLUSIONSThe expression inhibition of alpha 3 nAChR as a result of recombinant alpha 3 nAChR siRNA can induce oxidative stress and improve the toxicity of Abeta on SH-SY5Y cells, indicating that alpha 3 nAChR may play a significant neuroprotective role in the pathogenesis of Alzheimer disease.